PROJECT SUMMARY/ABSTRACT Unlike the dermis, the oral cavity is a site of privileged healing that does not significantly scar. Based on limited data, oral mucosal wound healing has been suggested as a model for exploring mammalian regeneration. In particular, oral mucosal fibroblasts exhibit unique characteristics when compared to dermal fibroblasts suggesting that these cells are programmed to facilitate scarless healing. Many parallels have been drawn between the oral mucosa and fetal skin which can also heal without scar formation. Oral mucosal fibroblasts share several characteristics with fetal dermal fibroblasts which have been recognized as a key component of scarless repair. Injured skin in the mammalian fetus heals scarlessly without myofibroblast involvement suggesting that smaller cellular forces contribute to regenerative repair. In vivo and in vitro studies have shown that fetal fibroblasts have unique characteristics that contribute to scarless healing including altered responses to ECM rigidity and defective signaling pathways. However, it is unknown whether oral mucosal fibroblasts also demonstrate this distinct phenotype and exhibit differential responses to environmental mechanical factors that induce myofibroblast differentiation in postnatal or ?adult? dermal fibroblasts which would represent a novel avenue of research for uncovering new mechanisms that drive scarless healing. Therefore, we hypothesize that oral mucosal fibroblasts have intrinsically altered mechanosensing mechanisms that limit their ability to transition into myofibroblasts. We will test this hypothesis in the following Specific Aims: (1) test the hypothesis that oral mucosal fibroblasts respond to physiologic biomechanical rigidities with an attenuated contractile response and (2) identify molecular differences in oral mucosal fibroblasts that can be targeted to reduce myofibroblast differentiation in adult dermal fibroblasts. We are taking an innovative approach by utilizing the mechanical phenotype of oral mucosal fibroblasts as a model for understanding regenerative repair. We will test our novel concept by using synthetic and biological substrates that mimic the different mechanical stages of wound healing that progressively induce myofibroblast differentiation to isolate the effects of physiologic rigidities. Overall, our goal is to delineate the underlying molecular and physical mechanisms by which oral mucosal fibroblasts may differentially mechanosense ECM rigidity by quantifying cellular biomechanical properties relevant to tissue repair. Furthermore, our research plan is designed to uncover potential molecular targets for novel treatment strategies for dermal scarring and fibrosis in postnatal wound healing. These studies are of particular clinical importance since no acceptable anti-fibrotic therapies currently exist and dermal scarring and fibrosis costs billions of dollars of year in medical care and management. In addition, the expected outcomes of our proposed studies are relevant to other fibrosis-related pathologies as well as to the fields of tissue engineering and regenerative medicine.